Refrigerator and /or freezer

ABSTRACT

The present invention relates to a refrigerator and/or freezer with a magnetic cooler, comprising a cold heat exchanger for cooling the cooling and/or freezing space of the appliance and means for detecting a value representative of the temperature of the cold heat exchanger, wherein the appliance includes a control or adjusting unit by means of which the temperature and/or the amount of the heat transfer medium supplied to the cold heat exchanger is adjustable such that in cooling operation the temperature of the cold heat exchanger does not go below 0° C.

The present invention relates to a refrigerator and/or freezer with amagnetic cooler, comprising a cold heat exchanger for cooling thecooling and/or freezing space of the appliance and means for detecting avalue representative of the temperature of the cold heat exchanger.

Refrigerators and/or freezers with magnetic cooling operate according tothe principle of the so-called magnetocaloric effect. It is known fromthe prior art that the magnetic cooler includes heat exchanger unitswhich are made of a material or include a material that is heated uponmagnetization and undergoes a decrease in temperature upondemagnetization. When a heat transfer medium, such as brine or analcohol mixture, is passed through the heat exchanger unit heated inthis way, it undergoes an increase in temperature. On the other hand,when it is passed through the cold heat exchanger unit, itcorrespondingly undergoes a decrease in temperature. The heat transfermedium cooled in this way then is passed through the so-called cold heatexchanger, which is arranged inside or in the vicinity of the coolingand/or freezing space and serves for cooling the same.

In prior art refrigerators and/or freezers it is common practice thatthe magnetic cooler with pump is switched off when a temperatureswitch-off value is reached. This means that the magnetic cooler and thepump are switched off when the heat exchanger or the space to be cooledhas reached a specified lower temperature value. With the magneticcooler and pump switched off, heating of the cooling and/or freezingspace and of the cold heat exchanger then is effected. Switching on themagnetic cooler with pump only will be effected again when the cold heatexchanger has been defrosted completely. Switching on again can forinstance be effected at a temperature of the cold heat exchanger of +5°C.

This procedure is disadvantageous in so far as the energy consumption ofthe appliance is comparatively high and in addition temperaturefluctuations exist due to the periodic operation of the magnetic coolerand the pump.

Therefore, it is the object underlying the present invention to developa refrigerator and/or freezer as mentioned above such that the same isimproved in terms of energy consumption, and in which temperaturefluctuations are avoided or reduced to a minimum.

This object is solved by a refrigerator and/or freezer with the featuresof claim 1. Accordingly, it is provided that the appliance includes acontrol or adjusting unit by means of which the temperature and/or theamount of the heat transfer medium supplied to the cold heat exchangeris adjustable such that in cooling operation the temperature of the coldheat exchanger does not go below +0° C. This means that the control oradjusting unit adjusts the refrigerating capacity such that the coldheat exchanger does not adopt a temperature of below 0° C., wherebyicing of the same can effectively be prevented. Due to the reducedrefrigerating capacity, the cold heat exchanger must be designedcomparatively large corresponding to the size of the cooling and/orfreezing space, in order to be able to provide the required cooling ingeneral.

The appliance can include a pump for delivering the heat transfermedium, and the control or adjusting unit can be configured such that itacts upon the delivery volume of the pump. It thus is conceivable, forinstance, to reduce the delivery volume of the pump, i.e. the rate ofdelivery of the heat transfer medium delivered by the pump, in order toensure that the cold heat exchanger does not reach temperatures of below0° C.

It is likewise conceivable that the control or adjusting unit isconfigured such that it acts upon the strength and/or position of themagnetic field present in the magnetic cooler. Thus, it is furthermoreconceivable to reduce the refrigerating capacity for instance byreducing the magnetic field. If a weaker magnetic field is present, themagnetocaloric effect is reduced correspondingly and the heat transfermedium flowing through the magnetic cooler is heated or cooled to areduced extent, so that the refrigerating capacity of the cold heatexchanger is reduced correspondingly.

In a further aspect of the invention it is provided that the control oradjusting unit is configured such that the delivery volume of the pumpand/or the magnetization in the magnetic cooler is effected independence on a control deviation, i.e. the deviation of the measuredvalue from a desired value or a range of desired values. If the measuredtemperature already lies within the range of the desired temperaturevalue, a change in the delivery volume of the pump or in themagnetization in the magnetic cooler may not be required, or an increaseor reduction of the delivery volume of the pump or of the strength ofthe magnetic field is considered in dependence on the control deviation.

Thus, it is conceivable to employ the delivery volume of the pump and/orthe strength or position of the magnetic field as control variables of acontrol circuit, whose setpoint represents a temperature value or also atemperature range.

One advantage of the present invention consists in that the magneticcooler and/or the pump for delivering the heat transfer medium can beconfigured such that they are running in continuous operation. This isdue to the fact that a defrosting cycle is not required in accordancewith the invention, since the cold heat exchanger is not, or at best fora short period, operated at temperatures below 0° C. If the temperatureof the cold heat exchanger nevertheless falls below 0° C., it can beprovided that a defrosting cycle is employed acyclically, if this isnecessary. The advantages of the invention consist in that due to theuniform and constant operation of the magnetic cooler and/or the pump,the energy consumption of the appliance is reduced as compared to priorart appliances, and that temperature fluctuations do not occur or onlyto a reduced extent.

1. A refrigerator and/or freezer with a magnetic cooler, comprising acold heat exchanger for cooling the cooling and/or freezing space of theappliance and means for detecting a value representative of thetemperature of the cold heat exchanger, wherein the appliance includes acontrol or adjusting unit by which the temperature and/or the amount ofthe heat transfer medium supplied to the cold heat exchanger isadjustable such that in cooling operation the temperature of the coldheat exchanger does not go below 0° C.
 2. The refrigerator and/orfreezer according to claim 1, wherein the appliance includes a pump fordelivering the heat transfer medium and that the control or adjustingunit is configured such that it varies the delivery volume of the pump.3. The refrigerator and/or freezer according to claim 1, wherein thecontrol or adjusting unit is configured such that it varies the strengthor position of the magnetic field acting in the magnetic cooler.
 4. Therefrigerator and/or freezer according to claim 1, wherein the control oradjusting unit is configured such that the temperature of the cold heatexchanger is adjusted to a specified desired value or within a range ofdesired values.
 5. The refrigerator and/or freezer according to claim 1,wherein the magnetic cooler and/or the pump are configured such thatthey are running in continuous operation.
 6. The refrigerator and/orfreezer according to claim 2, wherein the control or adjusting unit isconfigured such that it varies the strength or position of the magneticfield acting in the magnetic cooler.
 7. The refrigerator and/or freezeraccording to claim 6, wherein the control or adjusting unit isconfigured such that the temperature of the cold heat exchanger isadjusted to a specified desired value or within a range of desiredvalues.
 8. The refrigerator and/or freezer according to claim 2, whereinthe control or adjusting unit is configured such that the temperature ofthe cold heat exchanger is adjusted to a specified desired value orwithin a range of desired values.
 9. The refrigerator and/or freezeraccording to claim 3, wherein the control or adjusting unit isconfigured such that the temperature of the cold heat exchanger isadjusted to a specified desired value or within a range of desiredvalues.
 10. The refrigerator and/or freezer according to claim 9,wherein the magnetic cooler and/or the pump are configured such thatthey are running in continuous operation.
 11. The refrigerator and/orfreezer according to claim 8, wherein the magnetic cooler and/or thepump are configured such that they are running in continuous operation.12. The refrigerator and/or freezer according to claim 7, wherein themagnetic cooler and/or the pump are configured such that they arerunning in continuous operation.
 13. The refrigerator and/or freezeraccording to claim 6, wherein the magnetic cooler and/or the pump areconfigured such that they are running in continuous operation.
 14. Therefrigerator and/or freezer according to claim 4, wherein the magneticcooler and/or the pump are configured such that they are running incontinuous operation.
 15. The refrigerator and/or freezer according toclaim 3, wherein the magnetic cooler and/or the pump are configured suchthat they are running in continuous operation.
 16. The refrigeratorand/or freezer according to claim 2, wherein the magnetic cooler and/orthe pump are configured such that they are running in continuousoperation.